Question

A radio transmitter radiates $1kW$ power at a wavelength $198.6m$. How many photons does it emit per second?

• A. $\text{1}{0}^{\text{1}0}$
• B. $\text{1}{0}^{\text{2}0}$
• C. $\text{1}{0}^{\text{3}0}$
• D. $\text{1}{0}^{\text{4}0}$

Answer 1

Answer: (C)

$n=\frac{P}{E}=\frac{P}{hv}=\frac{P\lambda }{hc}$
$=\frac{1000\times 198.6}{6.6\times {10}^{-34}\times 3\times {10}^8}\approx {10}^{30}$